 <body onload="document.getElementById('a').style.minHeight='100%';">
<div style="overflow:auto; width:200px; position:absolute; height:200px;">
<div id=a style="position:absolute; width:300px; background:green">
</div>
</div>
 

<!-- 
<body onload="document.getElementById('fail').innerHTML = 'PASS';
              document.getElementById('tohide').style.display = 'none';">
<span id="fail">FAIL</span>
<span id="tohide">FAIL</span>
</body>

 -->